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The nature of black holes (BHs) and their potential deviations from classical General Relativity (GR) remain central questions in modern astrophysics. Nonlinear electrodynamics (NED) offers a promising mechanism to construct regular BHs…

General Relativity and Quantum Cosmology · Physics 2025-12-19 Javokhir Sharipov , Mirzabek Alloqulov , Pankaj Sheoran , Sanjar Shaymatov

The quantum black hole model with a self-gravitating spherically symmetric thin dust shell as a source is considered. The shell Hamiltonian constraint is written and the corresponding Schroedinger equation is obtained. This equation…

General Relativity and Quantum Cosmology · Physics 2007-05-23 V. A. Berezin , A. M. Boyarsky. A. Yu. Neronov

In this review, I have tried to focus on the development of the field, from the first speculations to the current lines of research. According to Einstein's theory of general relativity, black holes are relatively simple objects and…

High Energy Astrophysical Phenomena · Physics 2022-09-21 Cosimo Bambi

We present a rotating regular black hole whose inner horizon has zero surface gravity for any value of the spin parameter, and is therefore stable against mass inflation. Our metric is built by combining two successful strategies for…

General Relativity and Quantum Cosmology · Physics 2024-03-08 Edgardo Franzin , Stefano Liberati , Jacopo Mazza , Vania Vellucci

Horava gravity is a proposal for completing general relativity in the ultraviolet by interactions that violate Lorentz invariance at very high energies. We focus on (2+1)-dimensional projectable Horava gravity, a theory which is…

General Relativity and Quantum Cosmology · Physics 2021-12-20 Guillermo Lara , Mario Herrero-Valea , Enrico Barausse , Sergey M. Sibiryakov

A set of boundary conditions defining a non-rotating isolated horizon are given in Einstein-Maxwell theory. A space-time representing a black hole which itself is in equilibrium but whose exterior contains radiation admits such a horizon .…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Abhay Ashtekar , Christopher Beetle , Stephen Fairhurst

The study of astrophysical phenomena like black hole shadows is an effective approach to properly understand the modified gravity and explore its validity. Motivated by recent astrophysical observations, we consider a black hole (BH) in…

General Relativity and Quantum Cosmology · Physics 2025-03-20 Khadije Jafarzade , Zeynab Bazyar , Mubasher Jamil

We calculate the black hole mass distribution function that follows from the random emission of quanta by Hawking radiation and with this function we calculate the black hole mass fluctuation. From a complete different perspective we regard…

General Relativity and Quantum Cosmology · Physics 2020-03-10 Marcelo Schiffer

We consider a spherically symmetric black hole metric in (3+1)-dimensions in presence of a positive cosmological constant $\Lambda$. We use a general approach as proposed in \cite{1} to transform the metric in co-moving coordinates. Then…

General Relativity and Quantum Cosmology · Physics 2022-12-12 Anish Das , Ashis Saha , Sunandan Gangopadhyay

A class of observers is introduced that interpolate smoothly between the Schwarzschild observer, stable at spatial infinity, and the Kerr-Schild observer, who falls into a black hole. For these observers the passing of the event and inner…

General Physics · Physics 2024-05-31 Theodorus Maria Nieuwenhuizen

Generic extensions of the standard model predict the existence of ultralight bosonic degrees of freedom. Several ongoing experiments are aimed at detecting these particles or constraining their mass range. Here we show that massive vector…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Paolo Pani , Vitor Cardoso , Leonardo Gualtieri , Emanuele Berti , Akihiro Ishibashi

Quantum fluctuations of the spacetime metric induce an uncertainty in the horizon area of a black hole. Working in linearized quantum gravity, we derive the variance in the area of a four-dimensional Schwarzschild black hole from the…

High Energy Physics - Theory · Physics 2025-08-05 Maulik Parikh , Jude Pereira

The general parametrization of spherically symmetric and asymptotically flat black-hole spacetimes in arbitrary metric theories of gravity was suggested in [3]. The parametrization is based on the continued fraction expansion in terms of…

General Relativity and Quantum Cosmology · Physics 2022-05-18 R. A. Konoplya , A. Zhidenko

It has been argued by several authors, using different formalisms, that the quantum mechanical spectrum of black hole horizon area is discrete and uniformly spaced. Recently it was shown that two such approaches, namely the one involving…

High Energy Physics - Theory · Physics 2011-07-19 Saurya Das , P. Ramadevi , U. A. Yajnik , A. Sule

As a consequence of Birkhoff's theorem, the exterior gravitational field of a spherically symmetric star or black hole is always given by the Schwarzschild metric. In contrast, the exterior gravitational field of a rotating (axisymmetric)…

General Relativity and Quantum Cosmology · Physics 2022-09-22 R. Meinel

A generation method of new metric in the case of static spherically symmetric space-time is derived. Using this approach, we construct a metric which describes Euler-Heisenberg black hole surrounded by perfect fluid dark matter and…

General Relativity and Quantum Cosmology · Physics 2024-06-14 Shi-Jie Ma , Rui-Bo Wang , Jian-Bo Deng , Xian-Ru Hu

To ask a question about a black hole in quantum gravity, one must restrict initial or boundary data to ensure that a black hole is actually present. For two-dimensional dilaton gravity, and probably a much wider class of theories as well,…

General Relativity and Quantum Cosmology · Physics 2009-11-11 S. Carlip

Spacetime metrics describing `non-singular' black holes are commonly studied in the literature as effective modification to the Schwarzschild solution that mimic quantum gravity effects removing the central singularity. Here we point out…

General Relativity and Quantum Cosmology · Physics 2015-03-25 Tommaso De Lorenzo , Costantino Pacilio , Carlo Rovelli , Simone Speziale

We consider a new mass scale $M_{T}=(\hbar^{2}\sqrt{\Lambda}/G)^{1/3}$ constructed from dimensional analysis by using $G$, $\hbar$ and $\Lambda$ and discuss its physical interpretation. Based on the Generalized Uncertainty Relation, a black…

General Relativity and Quantum Cosmology · Physics 2016-06-22 Piyabut Burikham , Rujikorn Dhanawittayapol , Taum Wuthicharn

We propose a simple and unambiguous way to deduce the parameters of black holes which may reside in AGNs and some types of X-ray binaries. The black-hole mass and angular momentum are determined in physical units. The method is applicable…

Astrophysics · Physics 2015-06-24 O. Semerak , F. de Felice , V. Karas
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